Underfell Angel
by Blake Aster
Summary: She was his Light in his darkest hours. A vision his broken mind and created to help him deal with the pain. And now here she is. Real. Alive. His perfect Angel. Sequel to Underfell Fall
1. Chapter 1

**WARNINGS: Past non-con. Nothing graphic in this series, though.**

 **The beginning of the new series! Woo! We're following the story of the game, but with the Underfell twists that I read about when I looked it up. Very Sans-centric though. Definitely not as dark, at least not right now. I have an outline written out, but I have a tendency to change things as I write lol.**  
 **Anyways, I hope you enjoy! I want to say that I may not always be able to keep up the updating schedule that I had with the first part. And I suck at puns. I'm trying my best though!**

xxx

Everything was white.  
Not that it was anything new. Everything was always white in the forest outside the Ruins. Honestly, he wasn't sure why they even bothered putting sentries here. No one ever came here and no one ever left the Ruins. It was one of the few areas that was dust free, seeing as how monsters didn't exactly frequent that place since everyone moved. Normally, the sentry closest to the Ruins would be found asleep in his station, but not that day. That day he had felt the need to stretch his legs a bit. Take a walk.  
Said need may or may not have been because of the recent time anomalies.  
When the skeletal sentry found himself reliving the same events more than once, he had first suspected that damn flower of Alphys'. The yellow lizard had asked for his help the first time he had escaped, but he was too tired to be bothered.  
He was always too tired.  
But it was different the last couple of times. He didn't know how he knew, but he did. It felt different. Maybe it was the difference between the determination of a soulless creature and the determination of a human. But he knew.  
It was why that day of all days the sentry was standing in the woods, a few feet away from the path. His black hoodie was fringed with white fur over his blood red shirt that matched his red boots with black laces. Despite the weather, he stood there wearing block shorts that barely covered his knees. His face was spread in a constant grin, showing off his single, golden tooth among the razor sharp teeth. Should anyone look his way, they would be instantly struck with fear at the sight of his single, red, glowing eye in the dark.  
The door to the Ruins opened.  
Sans watched from afar as the human walked through, dressed in a black sweater with red stripes and jean shorts that they wer sure to regret later. Something about them stirred something in the back of his mind, but he couldn't place it. They were also wearing a black backpack. It was left open and sitting in it was that damned flower. He looked a little worse for wear, the sentry noticed.  
The human jumped when the Ruin doors closed behind them. The flower said something he couldn't hear and they moved on. The sentry stepped out of the trees and began to follow. They were speaking softly as they walked and the sentry noted that they were a little on edge. They practically jumped out of their skins when the sentry accidentally stepped on the branch that had fallen. They spun around quickly, but the sentry blinked away before they could spot him.  
He watched from the trees again as they took a moment to panic before moving forward. The sentry stepped out again and began to follow them. They eventually came up to the large, spiked gate the blocked the bridge that led across the chasm. Every spike was laced with a deadly poison and they protruded at every angle. It's creator had purposely made the bars too wide to make it tempting for people to skip through, but one false move and your life would be over.  
They noticed him coming. He could see it in the way they had stiffened. The sentry smirked and toyed with the buzzer in his hands. This was going to be easy. He approached, not even bothering to hide the noise of his footsteps. He walked until he was an arms length away from them.  
"Human. Don't you know how to greet a new pal?" the sentry asked with a deceptively friendly voice. "Turn around and shake my hand."  
The sentry already had his hand out and waiting as the human finally turned...  
...and his soul froze.  
She was the most beautiful thing he had ever seen. She had brown hair only a few shades darker than her tanned skin. Her eyes were narrow and black and her lips were plump. The only thing missing was her smile.  
Before the sentry could process this new information, the human had obediently taken his hand. He tried to bark out a warning, but it was too late. He watched as the electricity raced up her body and to her friend on her back. He watched as the life left her eyes before she crumbled to the ground. She now lay there before him, lifeless. The flower wasn't dead, but he had lost consciousness. Not that he cared.  
What he cared about what the human. This figment of his imagination that had come to life. The vision that had faded away long ago.  
His light.  
The sentry was standing in the trees.  
He was in a daze as his soul quivered with regret and confusion. His attention was drawn once again to the Ruin doors as they opened. They were more cautious this time. She kept looking around for threats. Without thinking, the sentry followed. The human didn't even bother to look this time when he broke the branch. He followed them all the way to the gate.  
"Human."  
She whirled around, weapon ready. It was a toy knife. This time, he noticed the red ribbon tied in her hair. She was on guard, but didn't attack. The sentry noticed that the knife didn't have a speck of dust on it. If it had been used to kill monsters, it hadn't been any time recently. The weapon shook in her hands and he could tell that she wasn't used to handling a weapon of any kind, even a plastic one.  
"Whoa there, buddy. No need to be so jumpy," the sentry told her. She didn't seem convinced. "You must have had quite the experience, to be so on edge."  
"Like you don't know, you smiley trash bag," the flower grumbled.  
"Long time no see, weed," the sentry growled. "I don't know what you're talking about. I mean no harm."  
"Oh? And what about that thing in your hand?" the flower snapped.  
"Oh, this?" the sentry held up his hand. "Just a harmless joke."  
"Yeah. Right," the flower hissed.  
The sentry shrugged.  
"So. What's your name kid?"  
She hesitated.  
"Come on, I ain't gonna bite. Okay, maybe a little," the sentry grinned.  
"She hasn't said a word since she got here," the flower grumbled. "What makes you think she'll talk to you?"  
"Izzat so. I'm guess that means you don't know it either?" the flower didn't respond. "Don' matter, eh kid? The name's Sans by the way. Sans the skeleton."


	2. Chapter 2

**Just a warning, I won't be following any script here. Conversations will be different, as they would be anyway seeing as how this is an AU in the first place.**

 _xxx_

" _The name's Sans by the way. Sans the skeleton."_

"I'm supposed to be on watch for humans right now, but I don't really care about catching any," Sans said with a yawn.

Too tired.

"Now my boss on the other hand, he's obsessed. He'd totally kill ya if he gets the chance. Sooo… I'm just gonna head on out. If he finds out I saw ya and didn't do nothin' he'd beat me senseless. So…"

The skeleton walked up to the gate. He pulled out a key and found the lock hidden carefully between two thorns. He unlocked the gate and swung it open. He grinned and waved at them.

"You guys have fun! Try not to get killed too fast, else boss'll be disappointed. And bored. Both of which are not conducive to my health. See ya later."

Sans walked away. Every bone in his body ached to turned around. To go to her. To stay by her side and protect her. But that wasn't how this world worked. It was kill or be killed. In this world, it was only a matter of time before his precious Light dimmed.

The thought made him stop in his tracks.

Why.

Why did it have to be her.

She didn't deserve this.

What did he know what she deserved.

He didn't know her.

 _I don't want to deal with this. I'm too tired to be dealing with this._

 _I'm so tired._

xxx

"SANS."

Sans groaned at the sound of his brother's voice. He stopped and rolled his entire head along with his eyes. He pouted at his brother, who was approaching with his usual confidence and head held high. His red cloak fluttered behind him as he walked. His outfit was black and red with spiked shoulder pads, tight pants, and tall boots. Sans was expecting the blow, but did nothing to avoid it when Papyrus' fist came crashing onto his head.

"YOU LAZY BUFFOON! WHAT HAVE YOU BEEN DOING THIS ENTIRE TIME?"

"My job, actually," Sans said.

"THAN WHY HAVEN'T YOU RECALIBRATED YOUR PUZZLES?"

Sans shrugged.

"Their fine."

"THEY ARE NOT FINE! WHAT IF A HUMAN COMES THROUGH?"

"I dunno. How 'bout we find out?"

Sure enough, the human walked into the clearing. Sans watched as his brother's eyes glowed with excitement. For the first time in forever, his brother laughed.

"Will you look at that. A human! Finally," Papyrus said. "At last, I'll finally be able to take Undyne's place as the leader of the Royal Guard. This is perfect, just perfect."

Papyrus cackled.

"Forgive me, I have been rude. I am the Great and Terrible Papyrus. Remember that name," Papyrus smirked. "For it is the name of the monster who will take your soul."

Sans felt a chill go up his spine. Papyrus turned and left without waiting for a response.

"This isn't good," the flower grumbled. "You need to give up this 'mercy' thing. He'll kill you before you even have a chance."

The human shook her head.

"You won't survive if you keep this up! Please, I'm begging you. You have to fight!"

The human hung her head low.

"I can give you some advice," Sans found himself saying. The human raised her head and looked right at him with hope filled eyes. Sans felt his heart melting. "Boss has this blue attack. You'll know it when you see it. When he uses it, don't move. No matter what."

The human nodded. Sans turned and began to walk away. He stopped when he felt someone grab his hand. For a panicked moment, Sans prepared to fire off a Gaster Blaster. He stopped when he saw the human there, with his hand still in hers.

She smiled.

For a moment, Sans felt like that boy again. That scared little boy. Afraid.

Alone.

Sans disappeared.


	3. Chapter 3

Sans doesn't even know why he was there, but there he was. Papyrus stood confidently as the human approached warily. Sans' soul quivered at the sight of her. She had a cut above her left eye that looked like it might still have been bleeding, ever so slightly. Part of him- the part that he had done his best to destroy less the cruel world around him destroyed him- wanted to go to her, to ease what little pain the small wound may be causing.

God, he hated himself.

"HALT, HUMAN!" Papyrus called. She stopped dead in her tracks. "COMMON COURTESY STATES THAT I MUST EXPLAIN HOW THIS BRILLIANT PUZZLE THAT I, THE TERRIBLE AND MAGNIFICENT PAPYRUS HAVE BUILT."

Papyrus motioned towards the patch of ground before them. It was in a perfect square with no ice or snow.

"TO BEGIN WITH, HERE WE HAVE ONE OF MY EASIER PUZZLES. BEFORE YOU LAYS A MAZE MADE WITH INVISIBLE, ELECTRIC FENCING. EVE NONE TOUCH IS FATAL! IF YOU CAN MAKE IT THROUGH, YOU MAY CONTINUE TO ONE OF MY MORE CHALLENGING PUZZLES."

"EASY? HOW IS THIS SUPPOSED TO BE EASY, YOU ASSHOLE!" the flower yelled. "If this is easy, I don't want to know what comes next!"

The human looked so terrified. Sans did his best to hide his sympathy. The last thing he wanted was for his brother to start suspecting something. However, the look of terror did stay long. She blinked and tilted her head. She looked like she was considered something. She gulped as she seemed to come to a decision and took a step forward… then to the right. Papyrus seemed to be in shock when, instead of walked through the maze she walked around the square clearing.

She came to stand a few feet before them, on the other side of the maze.

"THAT… THAT'S…"

Sans couldn't help himself. He burst out in laughter. Papyrus glared at him than at the human. He harrumphed and turned to leave without another word. The human looked a little worried, but the flower just smirked smugly.

"I gotta say…" Sans finally managed as he caught his breath. "...that was one way… to think… 'out of the box'! If you keep this up, you shouldn't have a problem finding your way 'around' the underground!"

She began to giggle.

It was a soft, gentle sound that made him feel… weird. He felt light and breathless- and not just front laughing so hard. He tried to think of something else- anything else- that he could say to make her make the sound again, but his mind had gone blank. God, what was she doing to him?

"Well uh… I'd better get going. Paps is gonna be sooo pissed! Man, you are about to have a real good time!"

Shit. Now she looks scared again. Maybe that's for the best. It's kill or be killed. The sooner she gets used to it, the better. If she wants to survive, she needs to give in.

The thought made him nauseous. What if she really did give in? What if she tainted her hands with dust?

What if this world erased her smile?


	4. Chapter 4

The boss was pissed.

Sans figured he would be when he dismantled his puzzle and put the sheet of paper down instead. He was glad his brother was always too obsessed with his own puzzles to pay attention to any of Sans' or else he would never have gotten away with this. He was still in major shit, but at least his brother would assume it was his laziness and not the soft spot he had for the human. This… thing that had his soul throbbing every time he saw her. She looked so cold…

The human is confused, but begins to pick up the paper.

"DON'T EVEN BOTHER! THIS IS A WASTE OF TIME!" Papyrus snaps.

Sans didn't miss the look he sent his way as Papyrus turned and stormed off. Oh, he was in so much trouble. He gave the human one more glance before following. She better appreciate the shit he's gonna have to put up with because of her. Not that she would ever know. She could never know.

No one could.

Xxx

The next puzzle made his bones ache with an old pain. Why Sans had chosen it was beyond Sans' understanding. It was one Gaster had built. He remembered how many times he had made Papyrus run the damn thing until he had it down perfect. Never Sans though. Too dangerous for the weak little monster with one HP.

Sans was barely paying attention as Papyrus explained how the puzzle worked to the human. The thought of her- of his perfect little Angel- having to endure this accused thing made his bones burn. The memories it reminded him of made his mouth taste like bile. Why would Papyrus do this to him? To his Light?

Sans blinked.

His?

He hadn't even realized he's been thinking of her like that.

But she was his.

His pure Angel of Light.

Sans tried to pretend to be surprised when the puzzle crashed. It wasn't like he had fiddled with it so that it wouldn't work or anything. Everyone was silent. Papyrus didn't even look mad this time. He just stared at the puzzle blankly before turning on his heels and walking away like nothing had happened. He didn't have to fake the puzzled look as he wand the human followed Papyrus with their eyes as he left.

"What is his deal?" the flower grumbled.

The human shrugged. She sighed in relief.

"You look tired. Should we take a break?" the flower asked.

The human shook her head. It wasn't the only part of her that was shaking. Sans swore he could hear her teeth chattering from where he was. Sans sighed.

He doubted either of them noticed him until his jacket had landed on her shoulder. Sans smirked as the flower's head was temporarily covered. The flower wriggled his way free, almost knocking the jacket free, but she grabbed it before it could.

"What's the big idea, you smiley trashbag?" the flower hissed.

Sans shrugged.

"The boss'll get bored if ya die cause you weren't wearing enough clothes and I don't see any other jackets just laying around. Not like I actually need it anyway," Sans said like it was obvious. The flower still looked suspicious.

She just smiled.

Sans didn't know if he wished she would stop doing that or not.


	5. Chapter 5

He decided he liked the way she looked in his jacket. It was too big for her. The sleeves were folded up but still nearly covered her fingers. The bottom of it reached her knees. She was adorable.

"How long do you plan to stare at us like some perv?" the flower asked.

Sans hoped he managed not to flinch at the last word.

Sans just grinned wider.

"Creep," the flower grumbled. Sans watched them move past him. A thought entered his head. He blinked and he was gone. He appeared again on the other side of the path. The human jumped when she saw him.

"What's up?" he asked.

The human turned and looked back to where he had she could finish the action, he was back to the other side. She jumped again, and he heard a squeak of surprise come out of her.

"Just ignore him," the flower said. "It's a crappy game he likes to play."

"Ah come on, I'm just tryin' to have some fun! No need to be such a 'pot'-ty mouth," Sans winked.

The flower rolled his eyes but she giggled. Sans' soul soared.

"Let's just go," the flower said.

Party pooper.

Xxx

For the first time, Sans had no idea what his brother had in mind. He didn't even know there was a puzzle on the bridge. That being the case, he was more than a little nervous when she stepped out onto the bridge

 **BEHOLD THE GAUNTLET OF DEADLY TERROR**

Sans watched in horror as numerous, deadly weapons appeared out of nowhere. Swords. Spears. Axes. (a dog…?) Of course, there was little to no reaction apparent on his face. He still had the same unnerving grin. Only the sweat dripping down his skull was any clue of what was going on under the surface.

"I HOPE YOU ARE READY. THERE IS ONLY A SLIGHT CHANCE OF SURVIVAL. THE MOMENT i ACTIVATE IT, EVEN THE SLIGHTEST INCH IN THE WRONG DIRECTION MEANS DEATH. I HOPE YOU ARE READY, BECAUSE I AM ABOUT TO ACTIVATE IT!"

Sans was ready. The moment those weapons started to move, he was ready to teleport her out of there. He couldn't let him hurt her. He couldn't…

Nothing happened.

Papyrus stood there. Stock still. The human looked as confused as Sans felt. Papyrus sighed and the weapons disappeared. What was going on?

"THIS PUZZLE… IS NO GOOD. THERE IS NO GRACE. NO INGENUITY. IT'S BORING. EVEN UNDYNE COULD COME UP WITH SOMETHING THIS MUNDANE."

With that Papyrus left. Sans didn't move. What… what was he doing? Risking everything for this… this human? Sure, he had seen those… those… visions of her, but they didn't mean anything. Just side effects of the determination. Those visions only showed him what she looked like. He didn't know anything about her as a person. This whole sweet, merciful thing could be a facade. He could just be manipulating them. She could be biding her time. She could…

Sans turned to leave.

He didn't know what to think anymore.

Xxx

Sans walked into the house he shared with his brother and shut the door behind him. He saw Papyrus on the couch, but didn't make any move to acknowledge him. He walked past him and went for the stairs. He just wanted to go to bed and forget. He was too tired for this shit.

He didn't feel the hit coming. He found himself laying flat on the ground. Papyrus loomed over him.

"DID YOU THINK I WOULDN'T NOTICE? I SEE THE WAY YOU LOOK AT HER. NO ONE ELSE MAY BE ABLE TO NOTICE, BUT I KNOW YOU BETTER THAN ANYONE."

"I… I don't know what your-"

Papyrus kicked him across the floor.

"YOU SABOTAGED MY PUZZLE YOU PURPOSEFULLY PULLED THAT CRAP WITH YOUR PUZZLE. YOU HAVE BEEN PROTECTING HER!"

"That's-"

"YOU ARE MY BROTHER, SANS," Papyrus growled. "YOU ARE MY MINE. IT LOOKS LIKE SOMEONE NEEDS TO REMIND YOU OF THAT FACT.

XXX

Sans didn't know how long he lay there in the middle of Snowdin. He could feel more than see the monsters passing him by. He couldn't help but wish that he hadn't gained so much LOVE. He would be dead and this would all be over. He felt someone stop nearby. Perhaps they were going to finish what Papyrus had started he hoped so.

He was so tired.


	6. Chapter 6

Honestly, Sans was surprised when he woke up again. He didn't think he was going to be getting back up that time. Admittedly, he kinda hoped he wouldn't. He wasn't in his room though. He wasn't even in his house. He recognized the roof. It wasn't the first time he had spent the night at the local inn. Usually when Papyrus had thrown him out or when Sans decided he needed a break from said monster.

"He's awake," a familiar, annoying voice said. There was sound of shuffling and a face came into view. His soul quivered. Again. He wished it would stop doing that.

"Hey, what's with that look?" Sans asked. She looked concerned. And sleep deprived.

"Don't be an asshole, asshole. She's been up all night looking after you. I told you you'd be fine after I healed you, but she wouldn't listen. Why she would give a damn about a trashbag like you is beyond me," the flower snorted. "OW! What was that for?"

The human glared at the flower with a pout. The flower grumbled something under his breath.

"Well… I'd better be gettin' back. Boss gets a bit 'bonely' when I'm not around."

Sans started to get up, but a hand on his chest stopped him. The human shook her head.

"Well, as much as I would love to have you as far away as possible, she isn't going to let you go until she's certain you are okay," the flower said.

"Uh huh. I could always… you…" Sans said. "...teleport away?"

"You could," the flower smirked knowingly. "But you won't."

Sans scowled. He flopped back down on the bed. The human smiled brightly.

"You might as well sleep. I have your Hp mostly restored, but some rest could do you some good," the flower said.

"Aww, if I didn't know any better I would think you were beginning to care," Sans said.

"Then you would be wrong, you smiling trash bag," the flower snapped.

The human giggled. He loved that sound. Realizing the direction his mind was going down again, he turned over onto his side away from the others in the room.

Xxx

The other two were asleep when he woke up again. She was in the other bed and the flower was on the nightstand between the two beds. He looked like he might have been playing lookout lest the monster in the other bed tried to hurt the damsel in the other bed. Like he's be able to do anything if Sans really wanted to hurt her.

Sans debated staying in bed, but decided he should really be heading back. Papyrus was pissed enough as is. He stood up and looked over to where his jacket was. It was hung on the coat rack in the corner of the room. She really did look good in it. Speaking of which, the human had turned over onto her back. She didn't have her sweater on, he realized. She was wearing a thin, plain, white, spaghetti-strap shirt. The blanket covered her lower half, but the thin shirt had ridden up to bare her midriff.

Sans gulped. He felt… strange. He felt like it was similar to something he felt before, but it was also different from anything he had never felt before as well. What surprised him the most though, was her tattoo. It was placed right above her heart. It looked like an upside down heart. Like a monster soul. Strange. Why would a human have a tatto of a monster's soul?

Sans couldn't help himself. He reached down to touch it. It was a feather light touch with very little actual contact, but it sent chills down his spine. What… what was this feeling? He didn't even notice he had moved until he was looming over her with one hand bracing himself next to her head. The human shifted in her sleep, causing the camisole to to slip, almost exposing one of her breasts.

Oh god. What the hell was this feeling?

 _Arousal._

Sans felt like someone had dumped a bucket of cold water over him. Not that he's know how that felt. He couldn't get away from her fast enough. He stumbled off the bed before teleporting away. He landed in his bedroom. He stood there for a moment, letting the realization of what had just happened sink in.

He fell to his knees and vomited.

Oh god. Oh god oh god oh god oh god. What the hell was wrong with him. He was disgusting. She was so pure and innocent. How could he even think about her that way? She didn't deserve that, least of all front someone as disgusting as him. He was a disgusting pile of shit.

Just like his father.


End file.
